When using an internal combustion engine as a source of power in vehicles, earth moving machines, etc., the power transmission has a central significance in practical conditions. The adaptation of the revolution speed of the engine and the cardan axle to each other so that on the cardan axle acts the torque required by the loading in the different driving situations requires the use of a transmission functioning at several gearing ratios. The different gearing ratios are obtained most usually by means of gear wheels. When the average driving speed in the European automobile traffic is estimated at 18.5 km/h, it means frequently repeated stops and shifting to different gears as well as plentiful driving at low gears and light engine loading. In these conditions, the fuel economy of the combustion engine is really poor and the power transmission losses are maximum, calculated in percentages. A decisive improvement would thus require the development of a transmission functioning in a wide gearing ratio range and steplessly, when the torque converting ratio can be changed in a smooth way according to the driving situations.